Multiscale Micro–Nano Nested Structures: Engineered Surface Morphology for Efficient Light Escaping in Organic Light-Emitting Diodes

Various micro-to-nanometer scale structures are extremely attractive for light escaping in organic light-emitting diodes. To develop and optimize such structures, an innovative approach was demonstrated for the first time to fabricate multiscale micro–nano nested structures by photolithography with a well-designed mask pattern followed by a controllable thermal reflow process. The experimental and theoretical characterizations verify that these unique nested structures hold the capability of light concentration, noticeable low haze, and efficient antireflection. As a proof-of-concept, the incorporation of this pattern onto the glass substrate efficiently facilitates light escaping from the device, resulting in current efficiency 1.60 times and external quantum efficiency 1.63 times that of a control flat device, respectively. Moreover, compared to a hexagonally arranged microlens array and quasi-random biomimetic moth eye nanostructures, the nested structures proposed here can magically tune the spatial emission profile to comply with the Lambertian radiation pattern. Hence, this novel structure is expected to be of great potential in related ubiquitous optoelectronic applications and provide scientific inspiration to other novel multiscale micro–nanostructure research

Synthesis, Crystal Analyses, Physical Properties, and Electroluminescent Behavior of Unsymmetrical Heterotwistacenes

Four novel unsymmetrical heteroacenes containing five-membered heterocycles (OPyN, TPyN, TPyC, TPyO) have been synthesized and characterized. The formed molecules exhibited twisted structures, determined by crystal analysis and showed blue/green fluorescence in dichloromethane and in thin film. Compounds OPyN and TPyN were selectively used as active ingredients, and the fabricated devices displayed promising electroluminescent performance

Synergy of W₁₈O₄₉ and Polyaniline for Smart Supercapacitor Electrode Integrated with Energy Level Indicating Functionality

Supercapacitors are important energy storage technologies in fields such as fuel-efficient transport and renewable energy. State-of-the-art supercapacitors are capable of supplanting conventional batteries in real applications, and supercapacitors with novel features and functionalities have been sought for years. Herein, we report the realization of a new concept, a smart supercapacitor, which functions as a normal supercapacitor in energy storage and also communicates the level of stored energy through multiple-stage pattern indications integrated into the device. The metal-oxide W₁₈O₄₉ and polyaniline constitute the pattern and background, respectively. Both materials possess excellent electrochemical and electrochromic behaviors and operate in different potential windows, −0.5–0 V (W₁₈O₄₉) and 0–0.8 V (polyaniline). The intricate cooperation of the two materials enables the supercapacitor to work in a widened, 1.3 V window while displaying variations in color schemes depending on the level of energy storage. We believe that our success in integrating this new functionality into a supercapacitor may open the door to significant opportunities in the development of future supercapacitors with imaginative and humanization features

0.7% Roll-off for Solution-Processed Blue Phosphorescent OLEDs with a Novel Electron Transport Material

A novel cross-linkable electron transport material, 1,3,5-tris­(5-(4-vinylphenyl)­pyridin-3-yl)­benzene (TV-TmPY), for solution-processing as well as a small molecule, 1,3,5-tris­(5-phenylpyridin-3-yl)­benzene (TmPY), for vacuum deposition were designed and synthesized for OLEDs. TV-TmPY and TmPY with identical core structures are fully characterized to systematically investigate the impact of solution processing and vacuum deposition on the performance of phosphorescent OLEDs. Over 90% EQE (external quantum efficiency) was achieved for the solution-processed TV-TmPY-based device compared to that of the vacuum-deposited TmPY at a luminance of 1000 cd m^–2. An EQE deviation of 0.7% was observed ranging from 100 to 1000 cd m^–2 with TV-TmPY, which is the smallest value to date for solution-processed OLEDs, and over 12% EQEs were achieved for the trilayered solution-processed green and blue phosphorescent OLEDs